THEORETICAL AND NUMERICAL STUDY ON VIBROA COUSUTIC BEHAVIOR OF INHOMOGENEOUS PLATES IN A CAVITY

Our work is concerned with acoustic transmission from the outside to t he inside of high speed train moving in a fluid ( such as two storey T .G.V. ) . The modelization of this problem leads us to consider a larg e structure, made of inhomogeneous plates putting together, and excite d by an aerodynamic (harmonic) source. In order to take into account t he principal phenomena wich govern our system, we study a simplified c onfiguration : An inhomogeneous plate, backed by a closed rectangular cavity. The theory is based on modal analysis of both plate and cavity uncoupled. The vibrations of the plate is analyzed with a RAYLEIGH-RI TZ approximation. The first numerical results provide some information s about the influence of the perturbation induced by heterogeneities : for instance, we can 't neglect the contribution of heterogeneities o n the internal acoustic pressure when the excitation is localised on i t (in the studied frequency field).